Alarm device



Nam '27, 1933. J. H. v. FINNEY 1,933,548

ALARM DEVICE Filed NOV. 1930 TO POWER CONTROL INVENTOR J. H. 1 F/NNEV 6% hum ATTORN EY Patented Nov. 7 1933 ALARM DEVICE John H. V. Finney, Denver, Colo, assignor, hy mesne assignments, to The More Company, Inc, New York, N. Y, a corporation oi Delaware Application November 1, 19369. @fill'ldtll No. 492,7d9

% Claims,

This invention relates to overload safety devices and more particularly to devices of this kind which are adapted for use with sedimentation apparatus, such as'thickeners of the Dorr 5 yp In the thickeners to which this invention is particularly applicable, a rotary rake structure acting to transfer the sludge at the bottom of a tank to a central outlet, is mounted on a vertical shaft which is rotated by means of a worm gear mounted thereon and a worm meshing with said worm gear. The moving parts of this apparatus are designed to move only a certain maximum amount of settled. solids having a creditormined resistance to the rake mechanism; and it sometimes occurs that due to excessive'feed; changes in'the character of the solids or changes in the proportion cl solids in the feed; or to more than one of these conditions; the settled solids build up to such an extent that the resistance offered to the raking mechanism is alsove that for which the mechanism was designed and tends to warp and break the mechanism. Such diirl- 'culties may also arise from obstruction to the rakes by foreign objects, such as tools, dropped into the tank.

Heretofore such thickeners have been pro= vided with devices responsive to increase of thrust of the worm above a predetermined point to signal the operator that excessive resistance to operation is being experienced by the raking mechanism. It has also been proposed to pro vide means for automatically throwing oil the power under such conditions thereby preventing damage to the raking mechanism. According to the present invention these desired results are effected by means particularly advantageous for producing the same and in addition there is provided a running signal which is effective while-the mechanism is not running.

The main object of the invention is to pro-= vide improved means for preventing damage under various conditions, to some of which refer once has already been made. A further object of the invention relates to the provision of for indicating that the rake StlfllCt'U"fi is worlr ing and which is immediately rendered ineffective for this purpose when the resistance be-= comes great enough to endanger the rake structure or mechanism.

Other objects and advantages will be apparent upon consideration of the following description and the accompanying drawing in which:

The figure is a view in iront elevation illustrating a preferred ernloocdnient the invers said opening in worin bracket and en ill; 19%11165) tion', parts being removed or broken away to show the underlying structure.

JPhe objects or the invention are in general attained by providing an alarm or danger signal,

a rumring or safety signal, a device for shutting w off the power and, means for throwing off said running signal and operating the alarm upon overload or resistance reaching an excessive or dangerous degree and for acting further and shutting off the power upon increase of overload $5 to a still more dangerous degree. in its preferred form the invention is embodied in a construction in which the shaft of a driving worm is yieldably supported against the thrust resulting from operation and serves to move an indi m cator accordance with the degree of such thrust or the degree of resistance to the movemerit of rake structure. Upon movement of the indicator to a predetermined position a circult controlling the safety signal is broken and a circuit for operating the alarm is closed, this condition being maintained until the overload is decreased to permit the indicator to move back sur'liciently to close the safety signal circuit and open the danger signal circuit, or until this condition is changed in some other way. if, how ever the overload increases so that the indicator moves past the point which it throws the danger signal into 0 oration and the running sig nal out of operation, and reaches a second predetermined point, another circuit is opened and the power is shut on.

Referring to the'drawing the worm 10, through which the worm wheel (not shown) connected with the rake structure (not shown) is driven, is rotated in the direction indicated by the arrow ll and, in driving the worm wheel, is subjected to thrust the direction of. arrow 12%. The worm in is fixed on a shaft it: of which the end toward which the acts enters an opening in the 9 worm gear bracket i i, and the thrust is transmitted through a thrust ball bearing 15, mounted on a reduced portion (not shown) of the shaft 13,

to a member id having a reduced portion entering ili Ill

movement within a relatively small range under normal load conditions.

Secured to an upright part of the worm gear bracket it is a bracket 23 of which the'lower end includes a yoke portion 24 extending horizontally away from the bracket i l and receiving the lower pivoted end of a pointer 25'mounted to swing in a vertical plane about the axis of a pivot 26 cirtending across the opening in said yoke portion and supported in the side thereof, the pointer being provided at its lower end with a set screw 27 which under normal working conditions is held in engagement with the thrust member 16. This set screw 2'? is threaded through the split lower end of the pointer and the pressure on the set screw may be regulated by means, such as a screw or bolt 28.

The means for maintaining the screw 2'? in engagement with the member 16 includes an eye bolt 29 connected with the pointer 25 (above the pivot 26) by means of a pivot or pin 30 passing through the eye of the bolt 29 and secured in the pointer. The shank of the bolt 29 passes through an opening in the yoke 24 and the bolt is urged outwardly or away from the pointer, by means of a spring 31 interposed between the yoke 24 and a cup washer 32 held on the shank of the eye bolt by suitable means such as nuts threaded on the end of the shank.

Extending upwardly from one side of the yoke 24 is an index bracket 33 having its upper end extended parallel to the path of the upper end of the pointer and in correspondence with the range of movement thereof, and this upper end maybe provided along an arcuate part thereof (adjacent to the path of the end of the pointer) with indications representing different load conditions.

The pointer 25 is also utilized to control an overload safety device which, according to the illustrated form, includes a control box 35 in which is slidably mounted a member or rod 36 adjacent to the plane of movement of the pointer and parallel thereto, and provided with stops 3'7 and 38 adjustably secured thereto by suitable means, such as set screws, and located on oppositesides of the pointer. Preferably these stops are so set that when the pointer is in its zero position (for example, when the machine is not running) it will be in engagement with the stop 37 and the member 36 will be at one end of its path of movement, and when the pointer in its movement away from its zero position reaches its middle position it will engage the stop 38. This position of the rod 36 will be maintained during normal operation of the thickener and may therefore be called its normal position.

Mounted in the control box 35 adjacent to the rod 36 is a plate or panel all which carries two circuit controlling devices or switches. these switches controls two circuits or branch cir-- cuits and includes a spring contact arm ll fixed at one end on a member or block 42 on the panel and arranged to engage a terminal l3 (adjacent to the rod 36) when permitted to do so and to engage a terminal l l when pressed away from the terminal d3. The fixed end of the contact arm or spring ll is connected with a conductor 5 in which is connected a suitable source of current, such as a battery is and the conductor 45 is connected at the far side from the contact spring ll with a shunt or branch line el'l' containing a run ning signal, such as a lamp 48, and connected wit? the terminal l3, with a shunt or branch line 4.9 containing an overload such an elec One of :eccaecc tric bell 50, and connected with the terminal i l. Preferably the spring contact ll is provided with a hump 51 to cooperate with a member 52 (of insulating material such as glass or percelain) mounted on the slidable rod and formed with a low portion 53 to permit t e contact part or member at the swinging end of the spring arm ll to engage the contact or terminal when the rod 36 is in normal position. and with high portion 54 connected with said low portion by means of a short incline so that upon movement of the indicator or pointer 25 to an overload position the hump 51 will ride up the incline to effect engagement of the terminal by the free end of the contact spring and will ride along the high portion to an extent determined by the movement of the pointer.

Upon the opposite side of the rod from the spring contact arm althere is provided a spring contact arm 55 fixedly mounted at one end on a block carried by the panel lil and connected at said block with one end of a power control circuit 56 of which the other end is connected with a terminal 57 carried by the panel in such a position that, when the arm 55 is moved outwardly from the bar 36 to a sufficient extent, it will engage such terminal and close the power control circuit to enable actuation of the shaft 13. Control of spring contact arm 55 may be effected by providing it with a hump 58 which during actuation of the shaft 13 is engaged by a high portion 59 of the cam member 52 to maintain the power control circuit in closed condition, but which upon sufficient movement of the rod 36 by movement of the pointer in an overload indicating direction will ride down an incline to open the power control circuit and rest on a, low portion 60 of the cam member. The high and low portions controlling the spring contact arms 41 and 55 are so arranged that upon increase oi. excessive overload the spring arm 41 will be shifted to throw off the running light 48 and to sound the alarm bell 50 and later, if the overload continues to increase the contact arm 55 will be shifted to open the power control circuit.

The operation of the overload safety device in connection with a thickener is substantially as follows: The thickener is started in any suitable manner when the parts are in the positions indicated in the drawing and during normal operation the pointer 25 may remain substantially stationary or may assume different positions between its zero position and its mid-position without producing any eflect on the safety device. If, however, the resistance to operation becomes errcessive (that is, an overload exists), the pointer 25 will engage the stop 3% and effect shifting of the rod 36 and consequently of the contact spring ll to open the circuit of the running light lamp l8 and close the circuit of the alarm or hell till. l

The operator may then clear up the dimculty or the difficulty may be remedied without any action on the part of the operator. lin either event the pointer would return to its normal range of move ment and consequently the alarm would be shut cline at the corresponding end oi? high per tion 59 and rest on the low portion to with its free end out of engagement with he te ninal "'l,

load the pointer will return to normal position and by engagement with the stop 37 will restore the other parts to their normal positions.

It shouldbe understood that various changes may be made in the,construction and arrange ment of parts without departing from the true spirit and scope of the invention. I

Having thus described my invention, I claim:-

1. Apparatus of the class described having a drive element, means for thrusting said drive element longitudinally upon encountering abnormal resistance, a motor circuit for driving said drive element, a switch for making and breaking said motor circuit, a reciprocable element unitary with said switch and movable in one direction to open said switch and movable in another direction to close said switch, a"pivoted lever operable by change of thrust on said drive element, and a selective connection between said reciprocable element and said switch for motivating said reciprocable element to open and close said switch during movement of said lever through certain portions of its path.

2. Apparatus of the class described having a drive element, means for thrusting said element longitudinally upon encountering abnormal resistance, a motor circuit for driving said drive element, a switch for making and breaking said motor circuit, a reciprocable rod unitary with said switch and movable in one direction to open said switch and movable in another direction to close said switch, a pivoted pointer operable by change of thrust on said drive element for motivating said rod, and stops on said rod to permit operable connection of said pointer with said rod during movement of said pointer through certain portions of its path.

JOHN H. V. FINNEY. 

